Topical sealers (surface coatings) are those that sit on the surface without penetrating it. They form a protective coating or film which gets fixed to the top of the concrete surface without any chemical reaction occurring between the sealer and the surface. Topical concrete sealers can help protect your concrete surface from water and oil stains and also damage caused by foot traffic.
However, since the topical concrete sealer is only on the top of the surface, the inside of the material will not be protected. Although the topical sealer protects your concrete surface from damage caused by foot traffic, it shows scratches, scuff marks, and abrasions especially in areas with high traffic because this concrete sealer is softer.
Generally, topical sealers or coatings change the texture of the surface that they are applied to. They reduce the traction, i.e., the surface becomes slippery when it is wet and you may need to add a non-slip additive if you are using a topical concrete sealer in areas like kitchens and bathrooms. Topical concrete sealers also change the appearance of the surface by adding color or gloss (i.e., low-gloss, high-gloss, matte, or satin finish) to the surface.
Topical concrete sealers not only protect the concrete surface from stains and chemicals but also visually enhance the surface. However, to be fixed properly, topical concrete sealers need to be applied on a clean and dry surface. But, because topical sealers find it difficult to bond with smooth surfaces, they must not be applied on polished surfaces.
Always choose a high-quality topical sealer, because lower-grade concrete sealers can turn yellow, especially when exposed to sunlight. Also, topical concrete sealers are not breathable, which causes moisture and water to be trapped within the surface and this can cause damage such as efflorescence, peeling, flaking, spalling, or cracking of the concrete surface.
Generally, topical concrete sealers are made from polyurethane or acrylic polymers and can be either water- or solvent-based. They are usually not very expensive as well. The life of topical sealers is general around 1 to 5 years, although urethane and epoxy sealers can last much longer. This concrete sealer is extremely simple to apply; however, since it is only on the surface of the concrete, it experiences more wear and need more maintenance and also need to be reapplied more often compared to penetrating concrete sealers.
The build-up of the topical sealer on the concrete surface will cause the scrapes and scuff marks to show more easily and will also make the surface look like plastic or wax. And so, before every new application, the concrete sealer must be stripped off to prevent build up. While some of concrete sealers can be removed easily using a stripper, other concrete sealers made from epoxy and polyurethane polymers are more permanent and are difficult to remove.